1. Field of the Invention
This invention relates to pigmented high solid coatings containing viscosity reducing amounts of a hydrolyzable silane and a titanate ester.
2. Description of the Prior Art
Pigmented high solid coatings are known in the art. One approach towards producing high solid coatings has been the use of lower molecular weight resins, e.g. those having a weight average molecular weight less than about 10,000. Since the lower molecular weight resins have a lower initial viscosity than higher molecular weight materials, less solvent is required to reduce the coatings to usable viscosities. Other approaches known in the art include the use of reactive diluents such as low molecular weight alcohols or unsaturated materials which reduce the viscosity of the coatings but cure or dry along with the resin to minimize the amount of volatile materials given off.
Due to the strict air pollution regulations, and the cost involved in utilizing a solvent in a coating which is merely lost to the atmosphere upon the drying or curing of the coating, providing high solid coatings at the highest possible solids and lowest possible viscosities is vitally important.
It is often desirable to incorporate high levels of pigmentation into high solid coatings. First, the pigments, especially extender pigments, are typically much less expensive than the vehicle itself. Additionally, higher pigment levels provide better hiding and the ability to formulate the coatings to produce almost any desired gloss. Frequently, since the pigments often have better resistance to ultraviolet radiation than the film-forming vehicles, the addition of high levels of pigment can provide better durability and resistance to weathering than coatings having lower PVCs. The use of the higher PVC levels, however, results in increased viscosity due to the presence of the high levels of pigments. It would therefore be an advantage to provide reduced viscosities in these high solid, high PVC paints or to provide higher solids coatings at the same viscosities.
This invention involves the surprising discovery that a combination of a hydrolyzable silane and a titanate ester is very effective in reducing the viscosity of highly pigmented high solid coatings.
The use of organotitanates and organosilanes for treating inorganic particles or ceramic fibers has been known in the prior art. However, the synergistic combination of a silane and a titanate in high PVC, high solid coatings formulations has not been taught.